tune2fs Command

Adjust tunable filesystem parameters on ext2, ext3, and ext4 filesystems

Syntax: tune2fs [OPTIONS] device

Warning: The tune2fs command modifies filesystem parameters and should be used with caution. Always backup important data before making changes. Some operations require the filesystem to be unmounted.

Description

The tune2fs command allows system administrators to adjust various tunable filesystem parameters on Linux ext2, ext3, and ext4 filesystems. It can modify parameters such as the maximum mount count, check interval, reserved block count, filesystem label, and many other options that affect filesystem behavior and performance.

Note: Most tune2fs operations can be performed on mounted filesystems, but some changes may require unmounting the filesystem first. Always check the documentation for specific options.

Common Options

Option	Description
`-l`	List the contents of the filesystem superblock
`-L volume-label`	Set the volume label of the filesystem
`-c max-mount-counts`	Set maximum number of mounts between filesystem checks
`-C mount-count`	Set the number of times the filesystem has been mounted
`-i interval`	Set the maximal time between filesystem checks
`-j`	Add an ext3 journal to the filesystem
`-J journal-options`	Override default journal parameters
`-m reserved-blocks-percentage`	Set percentage of blocks reserved for super-user
`-r reserved-blocks-count`	Set number of reserved blocks
`-u user`	Set the user who can use reserved blocks
`-g group`	Set the group which can use reserved blocks
`-e errors-behavior`	Set behavior when errors are detected
`-f`	Force the operation to complete
`-o [^]mount-options`	Set or clear default mount options
`-U UUID`	Set the universally unique identifier (UUID)

Examples

Display filesystem information:

tune2fs -l /dev/sda1
# Shows detailed filesystem information

tune2fs -l /dev/sda1 | grep -i label
# Show only the filesystem label

Set filesystem label:

tune2fs -L "MyData" /dev/sda1
# Sets the filesystem label to "MyData"

tune2fs -L "" /dev/sda1
# Removes the filesystem label

Adjust reserved blocks:

tune2fs -m 1 /dev/sda1
# Set reserved blocks to 1% (default is 5%)

tune2fs -r 0 /dev/sda1
# Set reserved blocks count to 0

tune2fs -m 0 /dev/sda1
# Disable reserved blocks entirely

Set filesystem check intervals:

tune2fs -c 30 /dev/sda1
# Force fsck after 30 mounts

tune2fs -c 0 /dev/sda1
# Disable mount-count-based checking

tune2fs -i 0 /dev/sda1
# Disable time-based checking

tune2fs -i 1m /dev/sda1
# Set check interval to 1 month

Configure error behavior:

tune2fs -e continue /dev/sda1
# Continue on errors

tune2fs -e remount-ro /dev/sda1
# Remount read-only on errors

tune2fs -e panic /dev/sda1
# Panic on errors

Add journal to ext2 filesystem:

# Convert ext2 to ext3
tune2fs -j /dev/sda1

# Add journal with specific size
tune2fs -J size=32 /dev/sda1

# Add external journal
tune2fs -J device=/dev/sdb1 /dev/sda1

Set UUID:

tune2fs -U random /dev/sda1
# Generate and set a random UUID

tune2fs -U clear /dev/sda1
# Clear the UUID

tune2fs -U 12345678-1234-1234-1234-123456789012 /dev/sda1
# Set specific UUID

Configure default mount options:

tune2fs -o acl,user_xattr /dev/sda1
# Enable ACL and extended attributes

tune2fs -o ^acl /dev/sda1
# Disable ACL support

tune2fs -o journal_data /dev/sda1
# Enable data journaling

Set reserved block ownership:

tune2fs -u root /dev/sda1
# Set root as user for reserved blocks

tune2fs -g wheel /dev/sda1
# Set wheel group for reserved blocks

tune2fs -u 1000 -g 1000 /dev/sda1
# Set specific UID/GID for reserved blocks

Error Behavior Options

Option	Description
`continue`	Continue normal execution when errors are encountered
`remount-ro`	Remount the filesystem read-only when errors are encountered
`panic`	Cause a kernel panic when errors are encountered

Time Interval Formats

Format	Description	Example
`d`	Days	30d (30 days)
`w`	Weeks	4w (4 weeks)
`m`	Months	6m (6 months)
`y`	Years	1y (1 year)
`0`	Disable	0 (disabled)

Advanced Usage

Comprehensive filesystem optimization:

# Optimize for performance
tune2fs -m 1 -c 0 -i 0 /dev/sda1

# Set label and UUID
tune2fs -L "DataDrive" -U random /dev/sda1

# Configure for server use
tune2fs -m 1 -e remount-ro -o acl,user_xattr /dev/sda1

Backup and restore filesystem parameters:

# Backup current settings
tune2fs -l /dev/sda1 > filesystem_backup.txt

# View specific parameters
tune2fs -l /dev/sda1 | grep -E "(Reserved|Mount count|Check interval)"

Batch operations on multiple filesystems:

# Set same label pattern for multiple drives
for dev in /dev/sd{b,c,d}1; do
    tune2fs -L "Data$(basename $dev)" "$dev"
done

# Disable checking on all data drives
for dev in /dev/sd{b,c,d}1; do
    tune2fs -c 0 -i 0 "$dev"
done

Journal configuration:

# Create external journal
mke2fs -O journal_dev /dev/sdb1
tune2fs -J device=/dev/sdb1 /dev/sda1

# Set journal size for large filesystem
tune2fs -J size=128 /dev/sda1

Monitoring and Verification

Check filesystem status:

# View mount count and maximum
tune2fs -l /dev/sda1 | grep -i "mount count"

# Check reserved blocks
tune2fs -l /dev/sda1 | grep -i "reserved"

# View filesystem features
tune2fs -l /dev/sda1 | grep -i "filesystem features"

Verify changes:

# Before making changes
tune2fs -l /dev/sda1 | grep "Filesystem label"

# Make change
tune2fs -L "NewLabel" /dev/sda1

# Verify change
tune2fs -l /dev/sda1 | grep "Filesystem label"

Common Use Cases

Performance optimization: Reducing reserved blocks on data partitions
Maintenance scheduling: Adjusting filesystem check intervals
System identification: Setting meaningful filesystem labels
Error handling: Configuring appropriate error behavior
Storage management: Converting between ext2/ext3/ext4
Security configuration: Setting reserved block ownership
Backup preparation: Setting UUIDs for consistent mounting
Server optimization: Disabling unnecessary checks on stable systems

Best Practices

Always backup important data before making filesystem changes
Test changes on non-critical systems first
Document filesystem parameters before and after changes
Use meaningful labels for easy identification
Consider disabling time-based checks on stable servers
Set reserved blocks to 1% or less on large data partitions
Use appropriate error behavior for different filesystem types
Monitor filesystem health after making changes
Keep UUIDs unique across systems
Use external journals for high-performance requirements

Safety Considerations

Some operations may require unmounting the filesystem
Changing journal parameters can affect data integrity
Modifying error behavior affects system stability
Always verify changes with tune2fs -l
Keep backups of critical filesystem parameters
Test changes in non-production environments first

Related Commands: e2fsck, mke2fs, dumpe2fs, resize2fs, fsck

Linux Commands